Handheld electronic devices, such as personal digital assistants (PDAs), mobile phones, digital cameras, and the like, offer mobility and a variety of services to their respective users. While they are typically configured to transmit and receive data to and from other devices via a wired or wireless connection, most mobile communication devices can also provide Internet access, maintain a personal address book, provide messaging capabilities, capture digital images, and place phone calls. Many devices, in particular smart phones and PDAs, provide a calendaring and/or “to-do list” service that allows the user to calendar appointments and to enter tasks directly into the device or into a service in a remote server. The calendaring service can be configured to provide a reminder of an appointment or task to the user at or near the time the appointment has been scheduled.
Many mobile communication devices can also identify their respective locations within a certain range depending on the device and location identifying technique. Some devices can use a sophisticated position determining system, such as a Global Positioning System (GPS). The GPS is a satellite-based radio navigation system that uses signals from three or four satellites to compute the current latitude, longitude and elevation of a GPS receiver in the device anywhere on earth down to within a few meters. Other devices can use a location identifying technique based on which base station is servicing the device, that is, the location of the device is within a range of the base station from which a call is made. Other devices can use location identifying techniques based on triangulation between the device and at least two base stations.
The device's location, typically represented by geospatial coordinates, can be used in a variety of ways. For example, a mapping service can use the device's current location to provide street directions from the current location to a desired destination location. In addition, a street address or name corresponding to the geospatial coordinates can be associated with a task or an appointment that is scheduled to be performed at or near the location. For example, the user can associate a task on the to-do list, e.g., “pick up medicine,” with the street address or geospatial coordinates associated with a task location, e.g., the user's pharmacy. When the device detects that the user is within a certain distance of the task location, e.g., the pharmacy, the device can display a message reminding the user to perform the task, e.g., “pick up medicine.” Alternatively, a reminder can be issued when the device detects that the user is near the task location and is traveling in a trajectory leading to the task location.
Location-based task reminders are useful for prompting the user to perform tasks that are located nearby. Typically, the reminders are generated when the user comes within a predetermined fixed distance of the task location. This can be problematic because, if the predetermined distance is relatively large, e.g., 0.5 miles, and the user frequently spends time in the 0.5 mile region surrounding the task location, e.g., the user lives or works in the region, the user can be inundated with multiple reminders for the task. On the other hand, if the predetermined distance is relatively small, e.g., 0.1 miles, and the user rarely spends time in the region, let alone within 0.1 miles of the task location, the device might not provide a reminder at all. Both situations reduce the usefulness and convenience of location-based reminders.
To address this problem, some services allow the user to enter a reminder distance when the user calendars the task and task location. This approach, however, may not be helpful if the user is unfamiliar with the task location, or if another person other than the user is calendaring the task for the user. In any event, requiring the user to provide information in addition to the task/appointment and task location can be time-consuming and inconvenient.